“Cryptic” diagenesis and its implications for speleothem geochronologies


Material Information

“Cryptic” diagenesis and its implications for speleothem geochronologies
Series Title:
Quaternary International
Bajo, Petra
Hellstrom, John
Frisia, Silvia
Drysdale, Russell
Black, Jay
Woodhead, Jon
Borsato, Andrea
Zanchetta, Giovanni
Wallace, Malcolm W.
Regattieri, Eleonora
Haese, Ralf
Publication Date:


Subjects / Keywords:
Speleothems ( local )
U-Th Dating ( local )
Outliers ( local )
U-Loss ( local )
Micro-CT ( local )
Petrography ( local )
serial ( sobekcm )


Speleothems are usually considered as one of the most amenable palaeoclimate archives for U-series dating. A number of studies in recent years, however, report cases of diagenetic alteration which compromises the use of U-series systematics in speleothems, resulting in inaccurate U-Th ages. Here we present the results of a high-resolution U-Th dating study of a stalagmite (CC26) from Corchia Cave in Italy where we document a number of departures from an otherwise well-defined age-depth model, and explore potential causes for these outliers. Unlike examples illustrated in previous studies, CC26 contains no visible evidence of neomorphism, and appears, at least superficially, ideally suited to dating. Good reproducibility obtained between multi-aliquot U-Th analyses removes any possibility of analytical issues contributing to these outliers. Furthermore, replicate analyses of samples from the same stratigraphic layer yielded ages in stratigraphic sequence, implying very localized open-system behavior. Uranium loss is suggested as a causative mechanism on account of the fact that all the outliers are older than their assumed true age. A limited number of micro-voids were observed under micro-CT analyses, and it is proposed that these were pathways for U loss. Uranium-loss modelling allows us to constrain the possible timing of diagenetic alteration and indicates that the precursor for the outlier with the largest age discrepancy (309%) must have been aragonite. This study indicates that visibly unaltered speleothems may still contain small domains that have experienced post-depositional alteration. Such “cryptic” diagenesis, as recorded in this stalagmite, has implications for the constancy of accuracy of the U-series dating technique, and suggests a need for careful examination of speleothems prior to dating, particularly in low-resolution U-Th studies.
Original Version:
Quaternary International, Vol. 148 (2016-09-15).

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
This object is protected by copyright, and is made available here for research and educational purposes. Permission to reuse, publish, or reproduce the object beyond the bounds of Fair Use or other exemptions to copyright law must be obtained from the copyright holder.

USFLDC Membership

University of South Florida
Karst Information Portal

Postcard Information



Download Options


No images or PDF downloads are available for this resource.

Cite this item close


Cras ut cursus ante, a fringilla nunc. Mauris lorem nunc, cursus sit amet enim ac, vehicula vestibulum mi. Mauris viverra nisl vel enim faucibus porta. Praesent sit amet ornare diam, non finibus nulla.


Cras efficitur magna et sapien varius, luctus ullamcorper dolor convallis. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Fusce sit amet justo ut erat laoreet congue sed a ante.


Phasellus ornare in augue eu imperdiet. Donec malesuada sapien ante, at vehicula orci tempor molestie. Proin vitae urna elit. Pellentesque vitae nisi et diam euismod malesuada aliquet non erat.


Nunc fringilla dolor ut dictum placerat. Proin ac neque rutrum, consectetur ligula id, laoreet ligula. Nulla lorem massa, consectetur vitae consequat in, lobortis at dolor. Nunc sed leo odio.